When the supreme court makes a ruling on a case that serves to interpret a law passed by congress it is an example of?

Checks and balances 
supreme court is granted power to overturn congressional laws that violate constitution. the courts however should exercise judicial constrain while doing that, to ensure the do not injure the principle of separation of power. usually they all restrain themselves to comparing whether the new law contradict the establishment clauses which would require a referendum, or the wording and legal process was followed. This ensures congress is checked.